Tiny fossils set record for oldest flowerlike pollen

WAY-BACK POLLEN Not in such bad shape after 240 million years, a fossil pollen grain from northern Switzerland shows features, such as the texture of its outer surface, that tend to characterize fossil pollen merely 100 million or so years old.

Nubbly specks 243 million years old could be the oldest fossils of pollen grains yet found from close ancestors of today’s flowering plants.

The somewhat squashed spheres come from deposits dating from 3 million to 5 million years earlier than the previous record holders, says Peter Hochuli of the University of Zurich. The newly described fossils show some features of pollen grains more than 100 million years younger that are widely accepted as signs of flowering plants, or angiosperms, Hochuli says.

The pollen may have come from ancient near-relatives at the very stem of the angiosperm genealogical tree, Hochuli and a colleague say in the October Frontiers in Plant Science.

These fossils date from a poorly understood time in the history of flowering plants. Primitive seeds had already evolved in the ancestors of conifers and their relatives. Today’s flowering angiosperms form more-protected seeds coddled in botanical ovaries that ripen into fruits.

Widely accepted fossils from seed-pampering flowers don’t show up until starting roughly 139 million years ago. Yet DNA analyses often suggest angiosperms arose much earlier.